1. Field of the Invention
The present invention relates to a nipping-roller gap adjusting device in a newspaper rotary press.
2. Description of the Prior Art
In a newspaper rotary press, pairs of nipping rollers, each of which comprises a stationary roller and a movable roller that can move away from the stationary roller and approach the stationary roller, are used to feed a printed paper web to a folding device. In order to adapt to the number of folded sheets of paper web and a difference in the thickness of paper web, it is desirable that the gap of the nipping rollers be adjustable. Apparatuses disclosed in Japanese Patent Publication No. 2818161 and Japanese Published Unexamined Patent Application No. Hei-4(1992)-164780, for example, are known as apparatuses for adjusting the gap of nipping rollers.
In the prior art nipping-roller gap adjusting device disclosed in the former patent (Japanese Patent Publication No. 2818161), a pressing force directed toward the stationary roller side is given by a compression spring to a lever which supports a movable roller, and a stopper for gap adjustment sets the gap between the stationary roller and the movable roller. Furthermore, the movable roller is adapted to be detached from the stopper during the passage of a paper web.
More specifically, the rotational axis of one roller, which constitutes the stationary roller, is rotatably supported by a frame, and the other roller, which constitutes the movable roller, is installed side by side with respect to the stationary roller, and rotatably supported in the middle of a lever, one end of which is supported by a separate shaft provided in parallel to the roller axis. Furthermore, a gap adjusting means is connected to the other end of the lever. The gap adjusting means has an adjusting screw which is screwed to a bobbin nut installed at the other end of the lever. A sleeve is movably fitted onto the periphery of the adjusting screw, and a flange is installed at an end of the sleeve on the apparatus-frame side. Adjacent to this flame are fixed an engaging collar and a handle.
The flange of the sleeve, along with the engaging collar, constitutes a stopper; the two members, when brought into contact with each other, prevent the lever from moving toward the stationary roller side to a larger extent than necessary. Therefore, in a case where a web having a thickness larger than a set gap size passes, the end face of the engaging collar moves away from the end face of the flange of the sleeve, thereby generating a gap between the two. The rotary press is normally operated in this state. Furthermore, a male thread is provided on the peripheral surface of the sleeve, and the bobbin nut and a compression spring holder installed on the apparatus frame are screwed to the threaded portion of the sleeve. The compression spring is installed so that it is interposed between the compression spring holder and the lever.
The roll-gap adjustment setting by the roll gap adjusting device of the above construction is performed by rotating the adjusting screw by means of the handle, thereby to increase and decrease the distance between the bobbin nut installed on the other end of the lever and the bobbin nut installed in the apparatus frame. Furthermore, the pressing force is adjusted by rotating the compression spring holder screwed into the sleeve.
In the prior art disclosed in the latter patent (Japanese Published Unexamined Patent Application No. Hei-4(1992)-164780), there are provided a stationary roller, a movable roller, and a support member that can move the movable roller by means of an air cylinder. The gap of nipping rollers is set by adjusting the phase of this support member by means of an eccentric pin.
In setting the roller gap, the support member is first detached from the eccentric pin by operating the air cylinder. Next, by operating an index handle the eccentric pin is caused to undergo rotational displacement, thereby to set the gap between the stationary roller and the movable roller to a desired value. The air cylinder is then operated to bring the support member into contact with the eccentric pin. As a result, the gap between the stationary roller and the movable roller is adjusted to the desired gap.
With the prior-art nipping-roller gap adjusting device disclosed in the former patent, when gap adjustment is performed during operation by means of a swinging lever, special skills are required because of the swinging motion of the lever itself, and accurate adjustment is hard to be accomplished even by skilled operators. Furthermore, because the gap adjusting mechanism and the mechanism of adjusting the pressing force are integrally constructed, the gap adjusting mechanism are complex and a large number of pants are needed. Therefore, relatively frequent maintenance is necessary and the system is prone to troubles.
When a thick paper sheet with a thickness larger than a thickness setting, such as a spliced part of paper webs, passes, an impact load generated by the passage of the thick paper sheet is applied to the adjusting mechanism, posing the problem that irregularities such as deformation and misalignment occur in the adjusting mechanism. Furthermore, accumulation of paper dust, etc. on the adjusting screw portion makes gap adjustment impossible.
In the prior art disclosed in the latter patent, a machine in operation must be temporarily stopped to perform gap adjustment and hence gap adjustment during the operation of the machine is impossible. Furthermore, because the gap adjusting mechanism and the mechanism of adjusting the pressing force are integrally constructed, almost the same problems as with the prior art disclosed in the former arise although the gap adjusting device of the latter is a little simpler in construction than that of the former.
It is an object of the present invention to provide a nipping-roller gap adjusting device which solves various problems as mentioned above in a rotary press provided with nipping rollers as described above, and which enables the gap adjustment of nipping rollers to be easily and accurately performed by everyone with a machine kept in operation. It is another object of the invention is to provide a nipping-roller gap adjusting device which has a simplified nipping-roller gap adjusting mechanism and a simplified mechanism of adjusting a pressing force, which does not require much maintenance, and which is less apt to suffer breakdowns.
In the invention, there is provided a nipping-roller gap adjusting device for use in a rotary press provided with a roller rotatably installed in a prescribed position and another movable roller to form nipping rollers, wherein the movable roller can force a paper web passing through the two rollers onto the stationary roller. As the essential features of the invention this nipping-roller gap adjusting device comprises; a pair of supporting arms, one end of each of the supporting arms being swingably supported and the other end thereof rotatably supporting the movable roller; a pressing force imparting means which gives to the supporting arms a force working in such a direction that causes the movable roller to approach the stationary roller and which, at the same time, can adjust the magnitude of the pressing force; a minimum gap setting means which can set a minimum gap between the stationary roller and the movable roller; a gap adjusting means which adjusts the size of a gap between the stationary roller and the movable roller; and a fixed frame member which rotatably supports the stationary roller and on which the gap adjusting means is mounted.
As the essential features of the invention, the gap adjusting means comprises an eccentric cam rotatably installed on the peripheral surface of a bearing sleeve which is rotatably supports one roller and a worm gearing for the rotary operation of the cam.
A paper web passing through the two rollers is pressed against one roller by accomplishing angular displacement in a direction in which a pair of supporting arms rotatably supporting the other roller is caused to approach the one roller, through the use of the pressing force imparting means which is installed in the supporting arms and which can adjust the magnitude of a force working on the supporting arms, a minimum gap between the one roller and the other roller is set through the use of the minimum gap setting means, and the size of a gap between the two rollers is adjusted through the use of the gap adjusting means installed in a supporting member rotatably supporting the one roller. Furthermore, the pressing force is obtained by giving an adjustable resilience of a compression spring to the supporting arms.